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Characterization of acetohydroxyacid synthase from Mycobacterium tuberculosis and the identification of its new inhibitor from the screening of a chemical library
Author(s) -
Choi Kyoung-Jae,
Yu Yeon Gyu,
Hahn Hoh Gyu,
Choi Jung-Do,
Yoon Moon-Young
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.07.055
Subject(s) - enzyme , mycobacterium tuberculosis , biochemistry , isoleucine , valine , biosynthesis , acetolactate synthase , leucine , chemistry , amino acid , enzyme assay , growth inhibition , biology , tuberculosis , cell growth , medicine , pathology
Acetohydroxyacid synthase (AHAS) is a thiamin diphosphate‐ (ThDP‐) and FAD‐dependent enzyme that catalyzes the first common step in the biosynthetic pathway of the branched‐amino acids such as leucine, isoleucine, and valine. The genes of AHAS from Mycobacterium tuberculosis were cloned, and overexpressed in E. coli and purified to homogeneity. The purified AHAS from M. tuberculosis is effectively inhibited by pyrazosulfuron ethyl (PSE), an inhibitor of plant AHAS enzyme, with the IC 50 (inhibitory concentration 50%) of 0.87 μM. The kinetic parameters of M. tuberculosis AHAS were determined, and an enzyme activity assay system using 96‐well microplate was designed. After screening of a chemical library composed of 5600 compounds using the assay system, a new class of AHAS inhibitor was identified with the IC 50 in the range of 1.8–2.6 μM. One of the identified compounds (KHG20612) further showed growth inhibition activity against various strains of M. tuberculosis . The correlation of the inhibitory activity of the identified compound against AHAS to the cell growth inhibition activity suggested that AHAS might be served as a target protein for the development of novel anti‐tuberculosis therapeutics.